What happens to alleles located on different chromosomes?

• A. They assort independently
• B. They always travel together
• C. They cannot recombine
• D. They are always linked

Answer: (A)

Alleles located on different chromosomes assort independently during meiosis. Because these alleles reside on separate chromosomes, the way one chromosome is distributed to a gamete is not influenced by how another chromosome is distributed. This random, independent separation means the allele from one chromosome pairs with any allele from the other chromosome, yielding all possible allele combinations with equal likelihood. For example, if one gene has A or a and another gene on a different chromosome has B or b, the gametes can be AB, Ab, aB, or ab, independently of each other. In general, with n such genes on different chromosomes, there are 2^n possible gamete allele combinations. Only when genes are on the same chromosome do they show linkage, which can cause them to be inherited together more often than not; recombination between linked genes can still break that association, but that scenario doesn’t apply to alleles on different chromosomes.